This invention relates to a motor vehicle constraining apparatus for use on vehicle running simulation benches.
A bench of this type enables the vehicle running conditions to be reproduced in an environment of small dimensions comparable with the dimensions of the vehicle itself and allows the value of certain physical quantities to be measured during running. A bench of this type therefore comprises a runway on which the wheels of the vehicle rest and an apparatus to constrain this latter in such a manner as to prevent it moving forwards. For the running simulation provided by the bench to be valid, the constraining apparatus must allow some degrees of freedom of movement and manoeuvre, which although being of subsidiary order compared with the forward movement, are of fundamental importance in obtaining proper reproduction of the running behaviour. The movements which such an apparatus must allow are substantially the suspension movements (roll, pitch and translation in a direction substantially normal to the ground) and the attitude movements (lateral translation and yaw).
Currently used constraining apparatus normally comprises assemblies of flexible elements anchored in various ways to the vehicle body and passing about pulleys fixed to points somewhat distant for the body, so as to keep the direction of the constraints imposed by said elements constant even when the body moves. In other cases such constraining apparatus comprises lattice structures formed to generate a virtual constraint through the vehicle barycenter, these structures being positioned substantially laterally to the sides of the vehicle. The constraining apparatus of the aforesaid type has numerous drawbacks.
Firstly, such apparatus involves rather large masses and moments of inertia which cannot be totally ignored compared with those of the vehicle itself, thus altering the running conditions simulated by the bench and negatively influencing the measurements taken during the test. In addition, such apparatus is rather bulky and considerably reduces access to the vehicle under test. Furthermore, the operations involved in connecting the vehicle to such constraining apparatus are long and complicated and require particular care and caution.
Finally, such apparatus is not always able to provide rigorous virtual constraint of the barycenter of the vehicle and preserve all the degrees of freedom which this possesses under real operating conditions.